Plywood stand strength questions

czwannabe

New member
Advice, please!!!

I just picked up a 90gallon tank and stand from a friend of mine. He has had the tank running for a few years with no problems and just decided to upgrade to an in-wall tank. After bringing the stand over to my house I realized it was built using all 3/4" plywood. I only plan on running this tank for about 8-9 months before I have to move and will probably be building a new one. The tank is sitting on a 2x4 frame and that frame is supported by 3/4" ply see pictures for reference. Should I try to add 2x4's in the corners to possibly help hold the weight or do you guys think it's fine as is? Then tank had water in it when I picked it up so I know it currently stands fine.... am I over thinking this?

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Desert Sea

New member
The plywood in of itself is sufficiently strong enough to carry the weight. It’s the lateral load that could be imposed on it that would be in question only because it’s hard to tell how the jointery was done. There are pocket screws in the picture so my guess is that the pieces are butt jointed and not an interlocking joint like a mortise and tenon. A butt joint won’t provide as strong of a joint as a mortise and tenon. Until you get around to building your new stand, a piece of 3/8” or 1/2” plywood fastened on the back of the stand will provide more than enough lateral bracing. No need to add 2x’s to carry the weight.
 

Robgixxer

New member
The plywood in of itself is sufficiently strong enough to carry the weight. It's the lateral load that could be imposed on it that would be in question only because it's hard to tell how the jointery was done. There are pocket screws in the picture so my guess is that the pieces are butt jointed and not an interlocking joint like a mortise and tenon. A butt joint won't provide as strong of a joint as a mortise and tenon. Until you get around to building your new stand, a piece of 3/8" or 1/2" plywood fastened on the back of the stand will provide more than enough lateral bracing. No need to add 2x's to carry the weight.

I agree. Plywood is actually quite strong. I'm actually in the middle of a 280 gallon build. My entire tank wall unit is built from 3/4" poplar plywood. I'm double layered in the corners and the uprights where the doors close against with a 2x3 joisted top with a layer of 3/4 on top of that. Everything glued and interlocking joints. Considering I will have upwards of 2500 pounds sitting on top of it.
 

czwannabe

New member
The plywood in of itself is sufficiently strong enough to carry the weight. It's the lateral load that could be imposed on it that would be in question only because it's hard to tell how the jointery was done. There are pocket screws in the picture so my guess is that the pieces are butt jointed and not an interlocking joint like a mortise and tenon. A butt joint won't provide as strong of a joint as a mortise and tenon. Until you get around to building your new stand, a piece of 3/8" or 1/2" plywood fastened on the back of the stand will provide more than enough lateral bracing. No need to add 2x's to carry the weight.

Awesome, that's good to hear. I've been stressing on it just not sure what to do.
I think I'll buy a little wood for piece of mind.
 

czwannabe

New member
I agree. Plywood is actually quite strong. I'm actually in the middle of a 280 gallon build. My entire tank wall unit is built from 3/4" poplar plywood. I'm double layered in the corners and the uprights where the doors close against with a 2x3 joisted top with a layer of 3/4 on top of that. Everything glued and interlocking joints. Considering I will have upwards of 2500 pounds sitting on top of it.

Nice a 280!!! I'd be way too scared to build a stand for that without a 2x6 frame skinned in ply!
 

mcgyvr

New member
Nice a 280!!! I’d be way too scared to build a stand for that without a 2x6 frame skinned in ply!

:facepalm: :p

I always find it funny that the floor a stand is put on could carry less weight than the crazy stands some people make these days..
 

Robgixxer

New member
Nice a 280!!! I'd be way too scared to build a stand for that without a 2x6 frame skinned in ply!

I'll have to get some pictures up to show you what I mean. I dont think that I fully elaborated on the exact construction of the piece. I promise you the way this is engineered.... it will hold way more than what will be sitting on it. I'm in south Florida as well so I am all solid concrete and steel in my house. So I'm not worried about my floor taking the load. I've seen people put some massive tanks on floor joist type floors and it's like "if I walk over there to admire the tank am I going to be the straw to break the camels back and go through the floor?" Lol!
 
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